1. Field of the Invention
The present invention is for overcoming inter-cell interference in a multi-cell environment and improving performance for a receiver in a cell edge. Particularly, the present invention, which relates to a transmitter suitable to a case of nulling Other Cell Interference (OCI) in a receiver, relates to an apparatus and method for minimizing the entire system error.
2. Description of the Related Art
A terminal of a cell edge simultaneously receives not only a signal transmitted from its own cell but also signals of neighboring other cells. The signals received from the other cells act as interference, acting as a main cause of limiting the performance of the terminal. That is, there occurs a problem that Inter-Cell Interference (ICI) results in system capacity or throughput performance degradation and the like.
And, this problem works more seriously in a Multiple Input Multiple Output (MIMO) system. Accordingly, research on technologies for overcoming this ICI and improving performance is being carried out. This is exemplified as a codebook-based error minimization technique (quantization preprocessor) for a single user, and a codebook-based ICI reduction technique.
The quantization preprocessor, which is of a MIMO preprocessing technique of minimizing errors in a single cell, single user environment, does not take interference from neighboring cells into consideration. And, in a case where there are many receive antennas compared to the total number of transmission streams, a receiver can null OCI through a nulling filter. However, a transmission precoder (code word) is selected without considering the OCI-Nulling Filter (OCI-NF), so a problem occurs that the OCI-NF results in performance degradation.
The codebook-based ICI reduction technique, which is a technique of minimizing OCI using a precoder, brings about the improvement of a Signal to Noise and Interference Ratio (SINR). But, this technique cannot completely null interference, so there is a problem that, in a case where the size of interference is very large, it is unsuitable to real reception.